computer

Computer is a rare, largely archaic verb meaning to calculate or compute, historically used for reckoning dates — most famously the Church's method for calculating the date of Easter (le comput). Modern French almost always reaches for calculer instead.

• Les moines devaient computer la date de Pâques chaque année. — The monks had to calculate the date of Easter each year.
• Ce traité explique comment computer les éclipses. — This treatise explains how to calculate eclipses.
• On ne dit presque plus computer dans la langue courante. — Computer is almost never used in everyday language anymore.

This verb looks like it should mean 'to use a computer,' but it has nothing to do with computing devices — it's an old word for calculating, mostly seen in historical or ecclesiastical texts, not a modern false-friend trap so much as a rarity trap.